(064) Monitoring Results From a Postapproval Safety Study of Pfizer-BioNTech COVID-19 Vaccine in the United States: Vaccine Utilization and Incidence Rates of Myocarditis/Pericarditis

Publication Number: 401

Background: A postapproval safety study of Pfizer-BioNTech COVID-19 vaccine (BNT162b2) [EUPAS43468] is underway in the United States. The study uses claims and electronic health records data from 5 research partners (RPs) participating in the Sentinel System. Descriptive monitoring analyses were conducted to inform the final comparative analyses.

Objectives: To describe monitoring results for vaccine utilization and incidence rates (IR) of myocarditis/pericarditis (m/p) in BNT162b2 vaccinees.

Methods: Monitoring analyses were conducted using data from 11 December 2020 through 31 October 2021. Among BNT162b2 vaccinees with ≥ 365 days of prior health plan enrollment, the numbers of first and second doses were reported by age, history of COVID-19 before vaccination (using diagnosis codes or positive SARS-CoV-2 test results), and immunocompromised (IC) status (using diagnosis codes or pharmacy dispensings for immunocompromising conditions and medications). Unadjusted incidence rates of m/p (in the 1-21 days after vaccination, using diagnosis codes) and 95% confidence intervals (CI) were estimated by age, sex, and dose number.

Results: During the observation period, > 1.8 million first doses and > 1.5 million second doses of BNT162b2 were observed. Approximately 20% of vaccinees were identified as IC. Most vaccinees (71%) were aged 18-64 years, with the remainder aged ≥ 65 years (17%), 12-17 years (12%), or < 12 years ( < 0.1%). Approximately 9% of vaccinees had a history of COVID-19 before vaccination.

Among all vaccinees, the unadjusted IR of m/p per 100,000 person-years for dose 1 or 2 was 59.99 (95% CI, 49.48-72.06) and was higher for dose 2 (79.22 [95% CI, 61.51-100.43]) than for dose 1 (43.97 [95% CI, 32.19-58.65]). The highest unadjusted IRs of m/p per 100,000 person-years were among males receiving dose 2 who were aged 12-17 years (233.17 [95% CI, 116.40-417.21]) or aged 18-24 years (264.66 [95% CI, 114.26-521.49]).

Conclusions: The large number of BNT162b2 vaccinees will enable robust inferences for the final analyses. The relatively low number of doses in individuals aged ≥ 65 years reflects the age distribution of the RPs, while the low number of doses in individuals aged < 12 years is due to the timing of authorization of BNT162b2 (in October 2021 for individuals aged 5-11 years). Estimates of crude IR of m/p in BNT162b2 vaccinees were consistent with other studies, as was the observation of the highest IR after dose 2 in young males. As the observed prevalence of IC status (a subgroup of interest in the final analyses) in BNT162b2 vaccinees was higher than that of published estimates in the general population, consideration will be given to increase the specificity of the IC algorithm.